Venting closure and liner therefor



Jan, 20, 1953 G. R. MILLER, JR.,' x-:TAL 2,625,073

VENTING cLosURE AND LINER. THEREFOR Filed June So, 1948 GEORGE R. MILLER JR ARTHUR W. WElDNER Mr [Kfm www ' may have very harmful effects.

' of pressure development.

y is normally in the liquid phase. speaking, it is desirable to provide a venting clo- Patented Jan. 20, y.1953

UNITED STATES .PATENT OFFICE VENTING CLGSURE AND LINER THEREFOR George R. Miller, Jr., East Hcmpeld Township, Lancaster County, and Arthur W. Weidner, York, Pa., assignors to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Application June 3o, 194s, serial N0. 36,094

This invention relates to venting closures.

More particularly, the invention relates to a venting Yclosure having a liner capable of venting excess pressure developed in a. container hav- ,ing the closure applied thereto.

In the packaging of certain products, particularly bleaching solutions such as sodium hypochlorite, hydrogen peroxide, and the like, and

bleaching powders such as calcium'hypochlorite, there is a problem presented by the development of pressure Within containers holding such materials, which pressure may be due to the presence in the material of impurities, such as small. amounts of iron, copper, or organic material, which impurities cause decomposition of the products resulting in the evolution of gas which develops pressure in the container. The development of pressure may also be caused by storage of such containers in places in which they are subjected to elevated temperatures as the application lof fairly high temperatures to such materials also results in decomposition of at least a portion of the material resulting in the evolution of gases therefrom. Pressure development Within such containers is a definite hazard as excessive pressures have ofttimes resulted in sudden disintegratlon of Athe container with an explosive force which In addition, in many instances wherein pressure has developed and has not been relieved, sudden opening of the package results in 'a rapid discharge of its contents due to comparatively high pressures within the package. I

Various closures known to the art as venting closures have been proposed and used to overcome the problem of pressure developed within this type of package. These venting closures are, generally speaking, quite complicated and difcult to manufacture and, for that reason,

only a few of them have been employed commercially in an attempt Ato overcome the problem While closures have been developed whichy ventgas upon the 'development of comparatively high pressures within the container, there is also the problem of liquid leakage due to ineffective sealing. Since those instances wherein'the material packaged Generally 2 Claims. (Cl. 215-40) sure which vents so as to relieve excess pressure at a pressure of 10 to 15 pounds per square inch. In some instances, depending upon the particular product, the design of the container or package, and the like, venting at pressures of 5 to 10 pounds per square inch is desirable. An acceptable venting closure should vent up to pressures as high as those indicated above and should also have a valve action so that, upon release of the pressure,l there will be a sealing off of the remaining contents of the container to which the closure is applied.

In addition to the above-discussed problems of venting, While at the same time providing a seal after release of pressure, there is the requirement that such a closure be capable of convenient manufacture.

It is, accordingly, an object of this invention to provide a closure which is capable of relieving pressure developed in containers or packages for material which develops pressure under certain conditions. Y

A further object of this invention is the provision of a liner which may be employed in conjunction with a conventional closure, thereby rendering it capable of venting upon the development of pressure within a container to which it is applied.

Still another object of this invention is to provide a venting closure, the parts of which may be conveniently assembled in conventional equipment. These and other objects of this invention will become apparent to those skilled in the art upon becoming familiar with the following description when taken in conjunction with the accompanying drawing in which:

Figure 1 is an elevation of one embodiment of a venting liner made in accordance with our invention;

Figure 2 is a view in elevation of another embodiment of a liner made in accordance with our invention;

Figure 3 is a sectional view which illustrates one embodiment of a closure made in accordance with our invention containing a liner such as that shown in Figure 2 Figure 4 is a sectional view which illustrates a closure such as that shown in Figure 3 applied to a container; and

Figure 5 is a sectional view of a closure applied to a container illustrating the manner in which the venting takes place upon the development of pressure within the container.

Referring particularly to the embodiment shown in Figure 1, in accordance with our invention,

we provide a liner of spongy material such as sponge rubber. The rubber may be natural rubber or may be any of the well-known synthetic rubbers such as rubberlike polymers of butadiene, rubberlike copolymers of butadiene and styrene, rubberlike-copolymers of butadiene and acrylonitrile, rubberlike polymers of chloroprene, and the like. The spongy liner is provided with an impervious facing 2 which may be on the surface of the liner exposed to the container contents or, if desired, `may be both on the exposed and unexposed surface.

In the modification shown in Figure 2, a spongy material 3 is provided with an impervious facing layer 4 adhered to the spongy material by means of an adhesive layer 5. Thel facing material is advantageously a layer of impermeable natural or synthetic rubber. However, if desired, vit may be any of a number of synthetic materials such as vinyl chloride-vinyl acetate copolymers, vinylidene-chloride polymer and the like. The

.facing layer 4 is advantageously of such thickness that it does not conform to the face of the sponge as this results in loss of sealing eiciency. In other words thin films are not desirable as these films indent into the pores of the sponge thereby resulting in an improper' seal. We have obtained advantageous results utilizing a facing layer of .010 `to .080 thickness.

In assembling the closures of our invention, the liner and facing may be friction fitted in the closure, but, generally speaking, it is advantageous to employ an adhesive such as is illustrated in Figure 3. We have found that it is desirable to utilize an adhesive to secure the liner to the closure as the material is of the sponge rubber type and a friction t results in buckling of the liner, thereby reducing its efiiciency. As shown in Figure 3, the closure of our invention may include a liner comprised of a sponge rubber Ybacking 3 to lwhich is adhered facing layer 4 by means of adhesive layer 5. The liner is held in closure 6 by means of adhesive layer 1.

It is highly important in the practice of our invention to utilize a closure having at least a Vmedium length skirt as, in order to obtain a closure which is capable of venting upon the development of pressures up to to 10 pounds per square inch in the container to which the closure yis applied, it is desirable if not necessary that the skirt of the closure contact the bead of the container to which it is applied. VThis is illustrated in 4Figure 4 wherein the skirt B of the closure E rests upon bead 9 of the container. .If a short skirt closure .is employed, the normal tightening force utilized to apply vthe closure Vto the Vcontainer may be sufficiently great to compress or compact the sponge rubber backing of the liner to such an extent that the sponge or spring effect no longer exists and no venting takes place. We employ a medium or long skirt closure to advantage, the thickness of the over-all liner being adjustedaccordingly.

The venting action of the closure of our invention is illustrated in Figure 5. Upon development of pressure within the container, the liner is compressed to such an extent that an opening Ill is provided between the container lip il and the facing layer 4 of the liner. rIfhe gases -pass .through the opening and, generally speaking, follow the thread of the closure to the atmosphere. 'Upon release of the pressure, the sponge rubber backing material expands, thereby providing a tight seal as illustrated in Figure 4.

While a `variety of .-spongy materials such `as sponge rubber may be employed, it is highly advantageous to utilize a material of medium cell size. When large cell size Sponges are utilized, we have found that there is a tendency for the closure to leak because of venting at much less than critical venting pressures. If ya small cell size 'sponge is employed, there is a danger of no venting action in the critical pressure range as the material is too stiff to be compressed upon the development of critical venting pressures.

The closures o'f `our invention may be conveniently manufactured as the facing material may be adhered to the sponge rubber backing by means of a suitable adhesive such as the adhesive known as Vulcalock which is cyclicized rubber and hydrocarbon solvent or any of a number of rubber-resin adhesives, for example, an adhesive comprising a solvent, polychloroprene and a hydrocarbon resin. A laminated sheet may be made in this manner from which liners may be punched and applied .to the `cap which contains the adhesive required to adhere the liner to the closure.

`When a liner is .employed without a 'facing adhered thereto, the sponge rubber can be conveniently manufactured into a sheet in a molding operation, which operation imparts suicient impermeability to the outer surfaces of the sheet to enable its employment in the practice of our invention.

Brcadly speaking, therefore, the term rubber or its equivalent, as used herein, is intended to include natural and synthetic rubber. By the term synthetic rubber is meant those synthetic substances which are commonly referred to as synthetic rubbers and which have lphysical properties resembling those of natural rubber, as set forth, for example, in the definition of synthetic rubber appearing at `pages 3 to 4 of the Circular C427 of the United vStates Department of Commerce entitled Synthetic Rubbers: A Review of Their Compositions, Properties, and Uses by VLawrence A. Wood, issued June 25, 1940; and on page 9 of Natural and Synthetic Rubbers, by Harry L. Fisher, being Edgar Marburg Lectures of 194.1 presented before the forty-fourth annual meeting of the American Society for Testing Materials.

While our invention has been described with reference to certain particular embodiments, it is to be understood that vthe invention is not limited thereby. Therefore, changes, omissions, substitutions and/ or additions vmay be made without departing from the spirit of the invention as defined in the appended claims which are intended to be limited only as required by the priorart,

We claim:

1. In combination with a container having a bead, a threaded venting closure of at least medium length skirt having adhered thereto a liner comprised of a medium cell size sponge rubber materialhaving an impermeable surface adapted to be exposed to the container contents, theskirt of .said closureresting upon the bead of said contamer upon the application of a closure to said container with normal .tightening forces thereby ma1ntaining suflicient resilience in said liner to enable compression thereof upon the development of pressure within `said container whereby the pressure-developing gases may be released to the atmosphere around the threads of said closure.

2. In combinationwith a container having a bead,=a'threade'd venting closure having at least `.medium length-skirtand containing a ,1iner,ad-

hesively secured thereto, said liner including a REFERENCES CITED medium pore size Sponge rubber backing having The following references are of record in the adhered thereto a facing layer of impermeable me of this :patent: rubber of such thickness that the facing layer does not indent into the pores of said sponge upon ap- 5 UNITED STATES PATENTS plication of said closure to said container, the Number Name Date skirt of said closure resting upon the bead of said 1,431,871 Burnet Oct. 10, 1922 container thereby maintaining suicient resil- 1,548,899 Oyama Aug. 11, 1925 ience in said liner to enable compression there- 2,148,169 Merolle Feb. 21, 1939 of upon the development of pressure within said 10 2,238,681 Dorough 1 Apr. 15, 1941 container whereby the pressure-'developing gases 2,389,761 Burgeni Nov. 27, 1945 may be allowed to vent from said container and escape to the atmosphere around the threads of FOREIGN PATENTS Said Chmn-@ Number Country Date ARTHUR W. WEIDNER. 

